FIGS. 1 and 2 show a conventional heat exchanger which operates to exchange heat between a heat medium (for example, a cooling medium or a brine) flowing in the heat exchanger and air passing through the heat exchanger. A heat exchanger 21, as shown in FIG. 1, is comprised of a pair of header pipes 22 extending in parallel relation to each other, a plurality of tubes 23 disposed between the header pipes and connected to the header pipes at their end portions, a plurality of radiation fins 24 provided on the sides of the tubes, a pair of reinforcement members 25 disposed on the top and bottom radiation fins, and brackets 26 for supporting the heat exchanger which are attached to the upper and lower portions of each header pipe.
Each header pipe 22 is constructed from a straight pipe having a circular cross section. A plurality of connection holes 27 are formed on the periphery of the header pipe with a predetermined pitch in the axial direction of the header pipe. The end portion of each tube 23 is inserted into a corresponding connection hole 27. Both ends of each header pipe 22 are closed by caps 28. An inlet tube 29 for introducing the heat medium into heat exchanger 21 is connected to one of the header pipes 22, and an outlet tube 30 for discharging the heat medium out of heat exchanger 21 is connected to the other header pipe.
Each tube 23 is formed as a straight tube which is flattened in the horizontal direction. The end portions of tubes 23 are each inserted into a connection hole 27 of a header pipe 22, and fixed therein by, for example, brazing. Corrugated type radiation fins 24 are fixed on the upper and lower surfaces of each tube 23 by brazing.
Brackets 26 are provided for attaching the heat exchanger to an air conditioner structure or a body of a vehicle. Each bracket 26 has a U-shaped slot 31 defined in its end portion. A bolt or the like is inserted through the slot to attach the heat exchanger to the appropriate structure. Brackets 26 are fixed to header pipes 22 by brazing the curved portions of the brackets on the peripheries of the header pipes.
However, since connection holes 27 in such a conventional heat exchanger are formed on the periphery of header pipe 22 having a circular cross section, a special jig or tool is required for processing the holes. This operation causes the manufacturing of the header pipe to be expensive. Therefore, it is difficult to produce the heat exchanger inexpensively. In addition, defects are liable to occur while inserting and connecting tubes 23 into the header pipes, because it is difficult to form connection holes 27 at precise positions and with desired shapes.
Moreover, since brackets 26 for supporting the heat exchanger are welded or brazed directly onto the peripheries of header pipes 22, the shape of the brackets must be formed to correspond to the shape of the header pipes. Accordingly, the manufactured brackets are essentially restricted to one shape. Furthermore, the welding or brazing of the brackets 26 onto the peripheries of header pipes 22 is troublesome and causes the bracket attachment process to be inefficient.
Furthermore, since tube 23 is connected to header pipe 22 only at connection hole 27, tube 23 may be moved in the lateral direction of header pipe 22 by a relatively weak force. Accordingly, the whole shape of heat exchanger 21 may be deformed by a relatively weak force.
In addition, reinforcement member 25 disposed on the surface of radiation fin 24 can not be securely connected to header pipes 22 because the outer peripheral surface of header pipe 22 is curved. It does not thus sufficiently improve the overall strength of heat exchanger 21.